Technique for Monitoring Activity within an Integrated Circuit

ABSTRACT

A technique to monitor events within a computer system or integrated circuit. In one embodiment, a software-accessible event monitoring storage and hardware-specific monitoring logic are selectable and their corresponding outputs may be monitored by accessing a counter to count events corresponding to each of software-accessible storage and hardware-specific monitoring logic.

FIELD OF THE INVENTION

Embodiments of the invention relate generally to the field of information processing and more specifically, to the field of performance and event monitoring in computing systems and microprocessors.

BACKGROUND

Computer programs have benefited from performance and event monitoring in order to optimize code, provide performance information, and improve computing efficiency. Some prior art techniques may require function-specific hardware to monitor a particular activity, such as cache misses. This can be somewhat limiting and an inefficient use of hardware resources.

BRIEF DESCRIPTION OF THE DRAWINGS

Embodiments of the invention are illustrated by way of example, and not by way of limitation, in the Figures of the accompanying drawings and in which like reference numerals refer to similar elements and in which:

FIG. 1 illustrates a block diagram of a microprocessor, in which at least one embodiment of the invention may be used;

FIG. 2 illustrates a block diagram of a shared bus computer system, in which at least one embodiment of the invention may be used;

FIG. 3 illustrates a block diagram a point-to-point interconnect computer system, in which at least one embodiment of the invention may be used;

FIG. 4 illustrates a block diagram of logic, in which at least one embodiment of the invention may be implemented;

FIG. 5 is a flow diagram of operations that may be used for performing at least one embodiment of the invention.

DETAILED DESCRIPTION

FIG. 1 illustrates a microprocessor in which at least one embodiment of the invention may be used. In particular, FIG. 1 illustrates microprocessor 100 having one or more processor cores 105 and 110, each having associated therewith a local cache 107 and 113, respectively. Also illustrated in FIG. 1 is a shared cache memory 115 which may store versions of at least some of the information stored in each of the local caches 107 and 113. In some embodiments, microprocessor 100 may also include other logic not shown in FIG. 1, such as an integrated memory controller, integrated graphics controller, as well as other logic to perform other functions within a computer system, such as I/O control. In one embodiment, each microprocessor in a multi-processor system or each processor core in a multi-core processor may include or otherwise be associated with logic 119 to enable activity monitoring techniques, in accordance with at least one embodiment. The logic may include circuits to enable hardware-specific activity indicators to be monitored, re-configurable activity indicators to be monitored, or a combination thereof.

In one embodiment, logic may be used within or outside of an integrated circuit to allow both hardware-specific monitoring and software-configurable activity monitoring to assist in the improvement or optimization of software programs, such as applications, operating systems, BIOS, firmware, etc. For example, in one embodiment, the logic 119 includes a register or other storage in which occurences of some software event or events may be counted. For example, in one embodiment, a software routine may write a “1” into a monitoring register each time the routine is entered and cleared each time it is exited. The occurrence of the “1” or the clearing of the “1” may be counted to give an indication of how frequently the routine is invoked or exited. For example, the routine could be a handler or similar routine to tell programmers how often a particular fault or event yield is invoked. In one embodiment, the storage may contain a number of registers to store a number of indications of various software-configurable events, which of which may be counted along with hardware-specific monitoring events. In this manner, at least one embodiment of the invention allows for both non-configurable and re-configurable event and activity monitoring techniques to be used in conjunction with each other.

FIG. 2, for example, illustrates a front-side-bus (FSB) computer system in which one embodiment of the invention may be used. Any processor 201, 205, 210, or 215 may access information from any local level one (L1) cache memory 220, 225, 230, 235, 240, 245, 250, 255 within or otherwise associated with one of the processor cores 223, 227, 233, 237, 243, 247, 253, 257. Furthermore, any processor 201, 205, 210, or 215 may access information from any one of the shared level two (L2) caches 203, 207, 213, 217 or from system memory 260 via chipset 265. One or more of the processors in FIG. 2 may include or otherwise be associated with logic 219 to monitor hardware-specific or software re-configurable activity.

In addition to the FSB computer system illustrated in FIG. 2, other system configurations may be used in conjunction with various embodiments of the invention, including point-to-point (P2P) interconnect systems and ring interconnect systems. The P2P system of FIG. 3, for example, may include several processors, of which only two, processors 370, 380 are shown by example. Processors 370, 380 may each include a local memory controller hub (MCH) 372, 382 to connect with memory 32, 34. Processors 370, 380 may exchange data via a point-to-point (PtP) interface 350 using PtP interface circuits 378, 388. Processors 370, 380 may each exchange data with a chipset 390 via individual PtP interfaces 352, 354 using point to point interface circuits 376, 394, 386, 398. Chipset 390 may also exchange data with a high-performance graphics circuit 338 via a high-performance graphics interface 339. Embodiments of the invention may be located within any processor having any number of processing cores, or within each of the PtP bus agents of FIG. 3. In one embodiment, any processor core may include or otherwise be associated with a local cache memory (not shown). Furthermore, a shared cache (not shown) may be included in either processor outside of both processors, yet connected with the processors via p2p interconnect, such that either or both processors' local cache information may be stored in the shared cache if a processor is placed into a low power mode. One or more of the processors or cores in FIG. 3 may include or otherwise be associated with logic 319 to monitor activity within a processor or other integrated circuit within the system. The logic may include or be associated with storage, such as one or more registers, to store software-configurable events, selection logic to choose between the software-configurable events and hardware-specific events, and one or more counters to count the occurrence of each.

FIG. 4 illustrates logic to perform at least one embodiment of the invention. In one embodiment, the logic 419 includes a register or other storage 401 to store indications of various events that occur within an integrated circuit or system with which it is associated. For example, in one embodiment, the storage may be a register to store a plurality of bits, each of which may be associated at any given time with a particular event that is to be monitored. For example, in one embodiment, one bit position of register 401 may store a bit that may be updated by a user's program or application, micro-code, a processor instruction, firmware, BIOS, or other code to indicate when the particular code performs a particular code segment or routine. For example, in one embodiment a bit of register 401 is set to a “1” whenever a routine, such as a handler routine, is entered, and set to a “0” whenever the handler routine exits. In other embodiments, other software-configured events may be monitored. Logic 419 also includes, in one embodiment, a selection logic 405 to select between the software-configurable event monitoring storage 401 and some other hardware-specific activity monitoring logic, such as logic to indicate when a cache miss occurs. The selection logic may be configured by a control register or storage 415, which causes the selection logic to select either the output of the software-configurable monitoring storage 401 or the hardware-specific activity monitoring logic output 407. Logic 419 may also include a counter 410 or storage area to store a count value for each of the events being monitored. For example, in one embodiment, counter 410 may be used to count the number of times a “1” is set or reset in one bit position of software-configurable event monitoring storage 401 in order to yield an idea of how many times a certain routine is entered or exited. Other occurances of other events may be counted by 419, depending on what bit within storage 401 is being counted or what hardware event output 407 is being selected and counted. Software can then read the counter 410 to gain some information about the monitored activity and adjust the code or hardware in response thereto.

In one embodiment, the counter 410 may be a number of counters, each working in conjunction or separately to count the various events. Event counter 410 may also be a timer counter to simply count up or count down a constant rate to time the difference between to two events occuring. For example, in one embodiment, the counter 410 starts counting at a constant rate when a “1” is written into a bit position of the software-configurable storage 401 indicating the start of a software routine, and the counter 410 stops counting when a “0” is entered in the same bit position of the storage 401, indicating the end of the software routine. Futhermore, storage 401 may include a number of memory locations or registers to store a number of different event occurance indications. In one embodiment, extra combination logic (not shown) may be used in conjunction with logic 419 to track indications of a number of or combinations of events. For example, in one embodiment, combination logic could be used to indicate when a software routine enters (as indicated in a bit of storage 401) and when some other hardware-specific function occurs (as indicated by signal 407). Other logic may be used in conjunction with logic 419 to provide further hardware-specific events, software-configurable events, or a combination thereof, to be monitored.

FIG. 5 illustrates a flow diagram of operations that may be used in conjunction with at least one embodiment of the invention, regardless of the processor or system configuration in which the embodiment is used. At operation 501, the software-configurable event storage or register is cleared. At operation 505, the selection storage or register is updated to select between a software-configurable event or hardware-specific event. At operation 510, the performance counter is cleared. At operation 515, code, such as a user program, micro-code, firmware, BIOS, etc, sets a “1” in a bit position of the software-configurable event storage when the event counter is to start counting and a “0” in that position when the event counter is to stop counting. At operation 520, software or some other agent may read the event counter to glean something about the performance of the event the counter was monitoring.

One or more aspects of at least one embodiment may be implemented by representative data stored on a machine-readable medium which represents various logic within the processor, which when read by a machine causes the machine to fabricate logic to perform the techniques described herein. Such representations, known as “IP cores” may be stored on a tangible, machine readable medium (“tape”) and supplied to various customers or manufacturing facilities to load into the fabrication machines that actually make the logic or processor.

Thus, a method and apparatus for directing micro-architectural memory region accesses has been described. It is to be understood that the above description is intended to be illustrative and not restrictive. Many other embodiments will be apparent to those of skill in the art upon reading and understanding the above description. The scope of the invention should, therefore, be determined with reference to the appended claims, along with the full scope of equivalents to which such claims are entitled. 

1. An apparatus comprising: a software-accessible storage to store an indication of a first event occuring within a software program; a selection logic to select between an output of the software-accessible storage or a hardware-specific monitoring logic; an event counter to increment or decrement after the occurrence of a first bit being set in the software-accessible storage and to stop decrementing or incrementing after the occurrence of the first bit being cleared.
 2. The apparatus of claim 1 wherein the event counter is to further count the occurrence of an event corresponding to either the hardware-specific monitoring logic, the software-accessible monitoring logic or both.
 3. The apparatus of claim 1 wherein the selection logic includes a software-accessible storage to control the selection logic.
 4. The apparatus of claim 1, wherein the software-accessible storage includes a register, whose bit locations each correspond to a different software event.
 5. The appatus of claim 4, wherein at least one bit of the bit locations is to store a “1” when a corresponding software routine starts, and a “0” when the corresponding software routine stops and the counter is to indicate a count between the start and stop of the software routine.
 6. A system comprising: a storage to store a software routine; a processor to perform the software routine; an activity monitoring logic to monitor the occurrence of the processor starting and completing the software routine, wherein the activity monitor includes a first register to store a bit corresponding to the start and end of the routine, a counter to count the time between the start and stop of the software routine, and a selection logic to select between an output of the first register and a hardware-specific monitor logic.
 7. The system of claim 6, wherein the hardware-specific monitoring logic includes logic to indicate a cache miss.
 8. The system of claim 6 wherein the selection logic includes a software-accessible storage to control the selection logic.
 9. The system of claim 6, wherein the first register is software-accessible storage and includes bit locations, each correspond to a different software event.
 9. A method comprising: clearing a software-accessible event storage; updating a selection control to select between a software-accessible event or hardware-specific event; clearing a performance monitor; setting a “1” in a bit position of a the software-accessible event storage when an event counter is to start counting and a “0” in that position when the event counter is to stop counting; reading the event counter.
 10. The method of claim 9 wherein the event counter is to further count the occurrence of an event corresponding to either a hardware-specific monitoring logic, the software-accessible monitoring logic or both.
 11. The method of claim 10 wherein select control includes a software-accessible storage.
 12. The method of claim 11, wherein the software-accessible storage includes a register, whose bit locations each correspond to a different software event.
 13. A machine-readable medium having stored thereon a set of instructions, which if performed by a machine cause the machine to perform a method comprising: clearing a software-accessible event storage; updating a selection control to select between a software-accessible event or hardware-specific event; clearing a performance monitor; setting a “1” in a bit position of a the software-accessible event storage when an event counter is to start counting and a “0” in that position when the event counter is to stop counting; reading the event counter.
 14. The machine-readable medium of claim 13 wherein the event counter is to further count the occurrence of an event corresponding to either a hardware-specific monitoring logic, the software-accessible monitoring logic or both.
 15. The machine-readable medium of claim 16 wherein select control includes a software-accessible storage.
 16. The machine-readable medium of claim 15, wherein the software-accessible storage includes a register, whose bit locations each correspond to a different software event. 